// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.search.query.profile;

import com.yahoo.processing.request.CompoundName;

/**
 * A query profile visitor which keeps track of name prefixes and can skip values outside a given prefix
 *
 * @author bratseth
 */
abstract class PrefixQueryProfileVisitor extends QueryProfileVisitor {

    /** Only call onValue/onQueryProfile for nodes having this prefix */
    private final CompoundName prefix;

    /** The current prefix, relative to prefix. */
    protected CompoundName currentPrefix = CompoundName.empty;

    private int prefixComponentIndex = -1;

    public PrefixQueryProfileVisitor(CompoundName prefix) {
        if (prefix == null)
            prefix = CompoundName.empty;
        this.prefix = prefix;
    }

    @Override
    public final void onQueryProfile(QueryProfile profile, DimensionBinding binding, QueryProfile owner) {
        if (prefixComponentIndex < prefix.size()) return; // Not in the prefix yet
        onQueryProfileInsidePrefix(profile, binding, owner);
    }

    protected abstract void onQueryProfileInsidePrefix(QueryProfile profile, DimensionBinding binding, QueryProfile owner);

    @Override
    public final boolean enter(String name) {
        prefixComponentIndex++;
        if (prefixComponentIndex-1 < prefix.size()) return true; // we're in the given prefix, which should not be included in the name
        currentPrefix = currentPrefix.append(name);
        return true;
    }

    @Override
    public final void leave(String name) {
        prefixComponentIndex--;
        if (prefixComponentIndex < prefix.size()) return; // we're in the given prefix, which should not be included in the name
        if ( ! name.isEmpty() && ! currentPrefix.isEmpty())
            currentPrefix = currentPrefix.first(currentPrefix.size() - 1);
    }

    /**
     * Returns the correct prefix component if we are still going down the prefix path,
     * or null to get all if we are inside the prefix
     */
    @Override
    public String getLocalKey() {
        if (prefixComponentIndex < prefix.size())
            return prefix.get(prefixComponentIndex);
        else
            return null;
    }

}
